The present invention relates to a sorting machine for grain products More particularly, it relates to such a sorting machine which has at least one sorting board arranged in an inclined fashion relative to the horizontal and vertical planes and driven in a reciprocating vibration in a plane which is suitable for sorting.
Sorting machines of the above mentioned general type are known in the art. One of such sorting machines is disclosed, for example, in the German document DE-AS 1,241,242. In this sorting machine the sorting board is provided with a rough upper surface which is favorable for separating of particles of a product to be sorted into separate streams. A supply unit for supplying a product to the sorting board is arranged in a highest region of the sorting board or the sorting boards, while a separating and withdrawing unit for the individual product fractions is arranged approximately in the region of the lowest corner of the sorting board or the sorting boards. The sorting board or boards together with the supply unit and/or separating and withdrawing units are assembled in a single sorting unit.
Under the action of the roughness and the oscillating movement of the sorting board the particles of the product are subjected to accelerations which result in a throwing movement. Because of the different specific weight or, in accordance with a new understanding of the process, the different sliding properties of the individual particles of the product, as well as the spatially inclined arrangement of the sorting board, several withdrawing streams which are separate from one another are formed with desired product fractions.
The above mentioned German document DE-AS 1,241,242 also discloses a sorting machine in which a co-oscillating supplying device is provided since it operates only with one sorting plate, and the product is fed in the region of the center of the upper longitudinal edge of the sorting plate. A somewhat different construction of the withdrawing region is provided, in that it has lateral product withdrawing troughs. For vibration of the sorting plate, a mechanically expensive construction is provided with a supporting frame for inclining the plate, and the supporting plate is articulately mounted on a base plate by means of two link pairs and oscillated by means of an outwardly engaging eccentric drive. Because of this construction, the eccentric drive must move considerable masses, which leads to a premature wear and application of considerable reaction forces to the base plate or the ground which supports the machine. Also, the possible oscillation frequency is limited by the relatively high mass forces. Finally, an additional inclination adjustment of the whole structure on a support frame and sorting plate by lifting or lowering of the foot point of the link pairs which lie farthest from the eccentric drive is provided. These foot points take up static and dynamic forces which additionally load the adjusting drive. In addition, this inclination adjustment acts substantially in the region of the upper reversing point of the sorting plate and therefore is limited to the change of only one inclination plane of the plate, which substantially limits the adjustment to different products to be sorted.
Another sorting machine is disclosed in the German document DE-OS 3,507,073. In this grain product sorting machine, a certain adjustment of the above described machine to modern conventional outputs is provided, however, with relatively high expenses. In addition to the fact that the sorting plates are assembled in stacks and a suppporting frame with links in the sense of the DE-AS 1,241,242 is no longer provided, the known grained product sorting machine also has an eccentric drive which is connected especially in highly oscillating units or sieve stacks, with mass forces of considerable magnitude. These forces are transferred to the complicated base frame provided for this reason with numerous reinforcements and also to the planes of installment and its environment in a disturbing manner. Further, the eccentric drive possesses the disadvantages in that it is subjected to mechanical wear and requires the maintenance. Furthermore, for force transmission of the eccentric drive and for supporting through expensive supporting units extending partially upwardly and downwardly in the base frame, the sieve stack is surrounded by U-profiles in a cage-like manner. The U-profiles are fixedly screwed with each individual sorting plate, so that a plate exchange for example in connection with an exchange of the product to be sorted or renovation, can be dismounted only with considerable mounting expenses. Finally, this machine is provided with additional inclination adjustment of the sieve stack only about one axis, and the adjusting device provided with numerous levers, links and threaded spindles is acted by the swinging units or the sieve stack not in exactly advantageous manner. Also, the accessability of the associated adjusting wheels is not optimal.